Gel stain is a really great product to use in the place of traditional stains. You are almost unlimited on the types of finishes you can do.
Coat what you want to stain with a paint first, (you might want to experiment on a piece of junk wood first to figure out what outcome you want)
When you start coating with the stain, usually with a cotton rag, the lighter you press down, the darker it will come out. Pressing hard will leave it lighter. Most of the time, it is better to apply several light, fast-drying coats rather than a heavy coat that takes a long time to dry and risks running.
Try different colors, I've seen many colors used as bases with very light gel stains applied over them with really amazing results.
I have even seen one of my friends use coffee grounds to stain the walls in his living room....but that's another story...
For me, this is the best product to use on fiberglass doors or even doors that only have primer. It is very easy to use and apply, it can make you look like an expert in no time!
I have found that taking regular breaks and stepping back to look at your work will help keep you on track and keep a uniform look. Always compare your work with the first section you started! It's easy to get lazy after half the job and lose the original feel and look. Press through to the end, you will be amazed.
Below in the first picture is some trim I'm working on today. A flooring company came in and left white trim against beautiful dark cabinets and I'm using gel stain to darken the trim to the cabinet color. It will probably take 3 coats.
The last picture is the product I'm using today.